Research And Analysis On Eccentrically Braced Frames With A Replaceable Web

Eccentrically braced frames (EBFs) have been widely used for tall buildings in recent years. Performance of EBFs depends primarily on ensuring that links serve as the primary energy-absorbing elements and keeping the main sections undamaged. Link beams will firstly yield and act as "fuses" when EBFs are attacked by a strong earthquake. Therefore, the structure may require extensive repair or replacement.To improve the performance of traditional links, the web and flanges were designed to separate from each other. The web was made of the low yield point steel while the flanges were made of high-strength steel. The web was connected to adjacent components with bolts. The analysis results showed that the web absorbed a large amount of energy and the flanges remained elastic under an earthquake with a proper design of the section dimensions and length of the links. The structure can be repaired by replacing the web only, and the residual deformation of the link was small after removing the web. Four major tasks were performed in order to meet the objectives of this research:(1) Cycling loading tests were performed on four links with variable length and height. Hysteretic behavior, rigidity degeneration, and energy-dissipation behavior were analyzed. Experimental study showed that these links exhibited very stable hysteresis characters, and the low yield point steel web yielded completely while the outside frame didn't buck. Therefore, this new type of link had a great prospect of engineering application.(2) Finite element analyses with the software of ABAQUS and variable parametric analyses were further conducted. The finite element analyses results agreed well with the experimental results. Additional study on the energy dissipation principle of the link and the load-bearing characteristic of bolts was carried out in the finite element analyses.(3) A simplified mechanical model was put forward and by the calculation of the elastic deformation of the flanges and the web, some references were provided to the application of this new type of link.(4) The influences of the height-width ratio of the web, steel grades of the web, and the flange stiffener were optimized parametrically to provide some advice to the future engineering design.